source code for node [Object Input]
Some nodes have similar "brothers", so a single py file that deals with all the "family".

It can be the same kind of node, but for several data types or slightly different operations. Usually, it is allowed to later switch to another type or operation inside the node or in the advanced panel (or hit U).



specifically about object input:

generic\data_input.py is used for any input. 

...\animation_nodes\nodes\generic\data_input.py




other generic nodes are found in eneric folder, but not only:


mix data and animate data deal with all float, vector etc types
in list you have create list and combine list (all list nodes switch type by connecting sockets etc so it's more obvious)
some nodes like math also can be directly searched or called as Add, Substract etc.
others too have "search tags" so that you can bring them by searching for slightly different name or bring them with a certain setting already on.


For example, rotation/convert rotations has several types of conversion, (euler to matrix, quaternion to axis angle etc) so in a search you can  already say "matrix" and see matrix to euler and it will bring the node with that specific setting on.